Piston pump

ABSTRACT

In a piston pump, in particular, for the pressure fluid conveyance in hydraulic, slip-controlled brake systems, comprising at least one piston, a suction valve and a pressure valve, it will be possible for the suction and pressure valves to be externally checked in that the suction valve and the pressure valve are formed on a structural unit adapted to be separately handled. Preferably, the structural unit comprises a sleeve-type section in which the piston is guided.

TECHNICAL FIELD

The present invention generally relates to piston pumps and moreparticularly relates to piston pumps for use with hydraulic,slip-controlled brake systems.

BACKGROUND OF THE INVENTION

A piston pump of the afore-described type has been taught, for example,by EP 0 631 050 B1. The state-of-the-art piston pump comprises apressure valve and a suction valve the two of which are arrangedseparately from one another within a pump housing and are of differentstructural designs. In addition, the conventional pressure and suctionvalves are successively mounted in the pump housing and, in mountedcondition, are permanently sealed therein in a way which precludesexamination (without destroying portions of the pump assembly). However,even prior to assembly thereof it is difficult to carry out an optimumcheck of the valves because to do so requires simulation of the valve inits assembled condition.

It is especially the examples of embodiment of a conventional pistonpump disclosed by FIGS. 11 through 19 of EP 0 631 050 that reveal apressure valve designed as a ball valve, wherein the ball is biasedagainst a seat formed as a radial bore, using an annular material. Thesaid prior art valve involves some disadvantages to the effect thatmounting of the annular material on the valve body of the pressure valveinvolves substantial efforts, and attachment thereof is not particularlystable. Moreover, the prior art arrangement does not prevent the valvebody from twisting, so that the ball is likely to slip from the valveseat or to cause a change in the preloading force.

Moreover, EP 0 631 050 discloses an axially arranged suction valveprestressed by a helical spring held by a spring cage, with the helicalspring and the holding element being located on the side of the suctionvalve facing the pressure chamber for which reason the brake fluid takenin has to be sucked through the spring coils, thereby substantiallyincreasing the flow resistance.

The problem underlying the present invention, therefore, resides inavoiding the disadvantages involved with the prior state of art, inparticular, to provide a piston pump wherein both the pressure valve andthe suction valve prior to assembly thereof in the pump housing can beexternally mounted and checked.

This problem, in the practice of the invention, is solved in that thepressure valve and the suction valve are formed within an individuallyhandled (i.e. self contained) structural unit.

One advantage of the present invention resides in that in view of theinventive design of the pressure valve and of the suction valve in theform of an externally mountable and checkable valve cartridge unit, thenumber of components employed and the number of scrap valves are reducedthereby decreasing the manufacturing costs. Moreover, it is an advantageof the invention that the time needed for assembling the piston pump ofthe invention is substantially reduced thereby equally decreasing themanufacturing costs. In addition, the structural combination of pressureand suction valves will result both in space savings and in an optimumuse of the space available for the valves within the pump housing. Thestructural combination of pressure and suction valves enables the valvebody to be simply bored as there is no need to accommodate separatevalves within the pump housing.

Preferably, the structural unit comprises a basic section and a sectionof sleeve-type configuration, it being especially the sleeve-typesection that contains a substantially axial bore for guiding the piston.The bearing surface of the piston is thereby insensitive to deformationoccurring by processing operations on the block. Moreover, the block isnot required to be anodized to obtain wear-resistance of the bearingsurface of the piston. In view of enhanced life requirements, wearresistance can, therefore, be improved only by a selection of materialsuitable for the structural unit.

A particularly cost-effective embodiment of the invention arises fromthe fact that the structural unit is secured within the housing of thepiston pump by caulking or clinching.

Under structural aspects, for example, for space saving reasons, it isadvantageous to form the pressure valve on the sleeve-type section andthe suction valve on the base section, with the suction valve beingarranged on the structural unit in axial and the pressure valve inradial relationship to the center axis.

According to a preferred embodiment of the invention, the structuralunit is made of a plastic material, such as PEEK. It is not only forcost-saving reasons that this material is to be preferred but alsobecause it permits to simultaneously mold valve elements. To thateffect, the substantially axial bore, preferably, is conically shaped toenable the material core to be extracted. Preferably, the piston is alsoconically shaped. The two cones, in the working point of the pump, areadjusted to the work cycle of cylinder bore and piston to insure minimumplay during operation of the pump.

Preferably, the structural unit is of a substantially constant diameterso that a simple bore within the pump housing will be adequate toaccommodate and secure the structural unit therein.

According to another preferred embodiment of the invention, the basesection is in the form of a separate unit. The extra costs involved withthis bipartite configuration of the structural unit are more thancompensated in view of the costs and manufacturing problems otherwiseconnected with the assembly of the suction valve within the structuralunit due to the small diameter of the cylinder bore.

According to a particularly preferred form of embodiment of the presentinvention, the pressure valve comprises a closure body and a valve seat,with the valve closure body being prestressed by a preloading elementagainst the valve seat thereof. To that effect, the preloading elementand the valve closure body can be integrally formed thereby preventingthe valve closure member from dropping during assembly and operation.

Advantageously, the preloading element is secured to the structuralunit. Moreover, it is preferred to form the preloading element on aclip, preferably a tongue, adapted to be plugged onto the structuralunit. The tongue can be made along with the clip, e.g. by punching.Moreover, the tongue insures that the contact pressure exerted on thevalve closure body be always in the vertical direction to preclude wearon the valve seat.

Advantageously, the clip can be pushed onto the structural unit. With adesign of the afore-described type, the preload on the valve closurebody will not be affected.

According to a preferred form of embodiment of the invention, the clipcomprises two sections extending in a direction substantially verticalwith respect to one another, with the first section being pushed overthe structural unit, and the second section being provided forpreloading the valve closure body, thereby eliminating the need forspecial mounting means on the structural unit; during assembly, the partof the clip serving for preloading is not used, thereby insuring anoptimum resilient effect. Preferably, the second section includes atongue substantially bent by 180°, thereby enabling a maximum resilientlength to be attained involving minimum space requirements.

According to a preferred embodiment of the invention, the valve seat isformed on a bore, with the valve closure body comprising a guidingsection for guiding the valve closure body within the bore, resultingnot only in a simplified assembly but also in reduced noise because theguiding section, during operation, will cause friction within the bore,thereby attenuating an oscillation of the valve closure body resultingin the generation of noise.

More advantageously, the preloading element is designed in the form of aleaf spring preferably extending in the longitudinal direction of thestructural unit, with the leaf spring preferably being secured to thestructural element externally of the bending zone thereof.

According to a further development of the invention, the suction valveof the piston pump comprises a valve closure body and a spring elementfor preloading the valve closure body against the valve seat thereof,with the spring element being located on the suction side of the suctionvalve, thereby substantially reducing the flow resistance during in-takeof the brake fluid as the latter need no longer be sucked, past thespring element, for example by the coils of a helical spring.

Advantageously, the valve closure body comprises a sealing section and aguiding section. No additional holding element for the spring element isrequired if means for bearing one end of the spring element are formedon the outer side of the guiding section.

According to a preferred form of embodiment of the invention permittinga preliminary assembly of the suction valve, an element is provided onwhich is formed the valve seat for the suction valve and which, inaddition, includes means for bearing the other end of the springelement.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematically shown sectional view of a piston pumpaccording to the invention;

FIG. 2 is a schematically shown longitudinal sectional view of a valvecartridge of the invention or a structural unit, respectively, accordingto a first embodiment of the present invention;

FIG. 3 is a schematically shown cross-sectional view taken along theline III—III of FIG. 2;

FIG. 4 is an individual view of a holding clip including a springaccording to the forms of embodiment of FIGS. 2 and 3;

FIG. 5 is a schematically shown longitudinal sectional view of a valvecartridge of the invention according to a second form of embodiment ofthe present invention;

FIG. 6 is a schematically shown longitudinal sectional view of astructural unit of the invention or a valve cartridge, respectively,according to a third embodiment of the present invention;

FIG. 7 is a schematically shown view of a valve cartridge of theinvention according to a fourth embodiment of the present invention;

FIG. 8 is a schematically shown cross-sectional view with no background,taken along the line VIII—VIII in FIG. 7;

FIG. 9 is a schematically shown longitudinal sectional view of a valvecartridge of the invention according to a fifth form of embodiment ofthe present invention;

FIG. 10 is a longitudinal sectional view of a partial section of a valvecartridge of the invention according to a sixth form of embodiment ofthe present invention;

FIG. 11 is a schematically shown cross-sectional view taken along theline XI—XI of FIG. 10;

FIG. 12 is a plan view of the pressure valve of the valve cartridge ofthe invention according to FIG. 10;

FIG. 13 is a schematically shown longitudinal sectional view of a valvecartridge of the invention according to a seventh form of embodiment ofthe present invention;

FIG. 14 is a cross-sectional view taken along the line XIV—XIV of FIG.13;

FIG. 15 is a schematically shown cross-sectional view taken along theline XV—XV of FIG. 13;

FIG. 16 is a schematically shown plan view of the valve cartridge of theinvention according to FIG. 13;

FIG. 17 is a schematically shown longitudinal sectional view of a valvecartridge of the invention according to an eight form of embodiment ofthe present invention;

FIG. 18 is a schematically shown cross-sectional view taken along theline XVIII—XVIII of FIG. 17;

FIG. 19 is a schematically shown longitudinal sectional view of a partof the valve cartridge of the invention according to a ninth form ofembodiment of the present invention;

FIG. 20 is a schematically shown cross-sectional view taken along theline XX—XX of FIG. 19;

FIG. 21 is a schematically shown longitudinal sectional view of a valvecartridge of the invention in accordance with the tenth form ofembodiment of the present invention;

FIG. 22 is a schematically shown cross-sectional view taken along theline XXII—XXII of FIG. 21;

FIG. 23 is a schematically shown longitudinal sectional view of a valvecartridge of the invention according to an eleventh form of embodimentof the present invention;

FIG. 24 is a schematically shown side view of the eleventh form ofembodiment of the present invention as shown in FIG. 23;

FIG. 25 is a schematically shown top view of the eleventh form ofembodiment of the present invention as shown in FIG. 23;

FIG. 26 is a schematically shown perspective view of the eleventh formof embodiment of the present invention as shown in FIG. 23;

FIG. 27 is a schematically shown longitudinal sectional view of a valvecartridge of the invention according to a twelfth form of embodimentaccording to the present invention;

FIG. 28 is a schematically shown longitudinal sectional view of a valvecartridge of the invention according to a thirteenth form of embodimentof the present invention;

FIG. 29 is a schematically shown cross-sectional view taken along theline XXIX—XXIX of FIG. 28;

FIG. 30 is a schematically shown top plan view of the thirteenth form ofembodiment of the present invention as shown in FIG. 28;

FIG. 31 is a schematically shown perspective view of the holding clipfor use with the thirteenth form of embodiment of the present inventionas shown in FIGS. 28 through 30;

FIG. 32 is a schematically shown perspective view of a variant of theholding clip shown in FIG. 31;

FIG. 33 is a schematically shown cross-sectional view corresponding tothe illustration in FIG. 29 showing the attachment of the holding clipillustrated in FIG. 32;

FIG. 34 is a schematically shown exploded view in longitudinal section,of a valve cartridge according to the fourteenth form of embodiment ofthe present invention;

FIG. 35 is a schematically shown longitudinal sectional view of thevalve cartridge according to FIG. 34 in assembled condition;

FIG. 36 is a schematically shown longitudinal sectional view of a valvecartridge of the invention in accordance with a fifteenth form ofembodiment of the present invention;

FIG. 37 is a schematically shown perspective view of a broken-awayillustration of the valve cartridge according to FIG. 36;

FIG. 38 is a schematically shown cross-sectional view of the valve bodyaccording to the fifteenth form of embodiment of the present inventionas shown in FIGS. 36 and 37;

FIG. 39 is a schematically shown side view of the valve body of theinvention according to FIG. 38;

FIG. 40 is a schematically shown perspective view of the valve bodyaccording to FIGS. 38 and 39;

FIG. 41 is a schematically shown top plan view of the valve body ofFIGS. 38 through 40;

FIG. 42 is a schematically shown longitudinal-sectional view of a valvecartridge of the invention in accordance with a sixteenth form ofembodiment of the present invention;

FIG. 43 is a schematically shown cross-sectional view taken along theline XLII—XLII of FIG. 42;

FIG. 44 is a schematically shown longitudinal sectional view of a valvecartridge of the invention in accordance with a seventeenth form ofembodiment of the present invention;

FIG. 45 is a schematically shown longitudinal sectional view of a valvecartridge of the invention in accordance with an eighteenth form ofembodiment of the present invention;

FIG. 46 is a schematically shown longitudinal sectional view of a valvecartridge of the invention in accordance with a nineteenth form ofembodiment of the present invention;

FIG. 47 is a schematically shown longitudinal sectional view of a valvecartridge in accordance with a twentieth form of embodiment of thepresent invention;

FIG. 48 is a schematically shown perspective view of a holding clip foruse with the twentieth form of embodiment of the present invention asshown in FIG. 47;

FIG. 49 is a longitudinal sectional view of a valve cartridge of theinvention in accordance with a twenty-first form of embodiment of thepresent invention;

FIG. 50 is a longitudinal sectional view of a valve cartridge of theinvention in accordance with a twenty-second form of embodiment of thepresent invention;

FIG. 51 is a top plan view of the valve cartridge according to FIG. 50,including a pressure valve of the invention;

FIG. 52 is a schematically shown side view of a leaf spring of thepressure valve of FIG. 51;

FIG. 53 is a longitudinal sectional view of a valve cartridge inaccordance with a twenty-third form of embodiment of the presentinvention;

FIG. 54 is a top plan view of the valve cartridge of FIG. 53, includingthe pressure valve of the invention;

FIG. 55 is a schematically shown side view of a leaf spring of thepressure valve of FIG. 54;

FIG. 56 is a longitudinal sectional view of a valve cartridge of theinvention in accordance with a twenty-forth form of embodiment of thepresent invention;

FIG. 57 is a side view of the valve cartridge of FIG. 56, including apressure valve of the invention; and

FIG. 58 is a cross-sectional view with valve cartridge, piston and leafspring of the pressure valve of FIG. 57, taken along the line A—A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 schematically shows a sectional view of a piston pump 1 accordingto the invention, which is especially suitable for use with ananti-locking brake system (ABS), a traction slip control (ASR) or anelectronic stability program (ESP) of a slip-controlled automotive brakesystem. The piston pump 1 according to the sectional view of FIG. 1 isdesigned substantially in symmetry with the center line M. The pistonpump 1 comprises, in the housing thereof, a driving shaft 3 actuated byan electric motor (not shown). An eccentric cam 4 located on the drivingshaft 3 is in abutment with pump pistons 5 interconnected, for example,via a coupling ring. The rotary movement of the driving shaft 3 istransformed by the eccentric cam 4 into a stroke of pistons 5.

The pump housing 2, in addition, comprises at least one bore 6preferably stepped in which is respectively arranged a structural unitor a valve cartridge 7. In accordance with the invention, the structuralunit 7 is secured, in pressure-tight manner, within the pump housing 2,preferably by means of caulking or clinching. The valve cartridge 7,preferably, is made of a plastic material although it can also consistof a different suitable material. The valve cartridge or the structuralunit 7, respectively, comprises a substantially sleeve-type section 8which, relative to the center line M is the inner section, and a section9 or base section 9 which, relative to the center line M is the outersection. The sleeve-type section 8 which can also be designated by a lugor extension of the cartridge 7, in accordance with the invention,serves as a guiding or bearing surface for the pump piston 5.

In the practice of the invention, valve seats for a pressure-controlledsuction valve 10 and a pressure-controlled pressure valve 11 are formedon the structural unit 7. The suction valve 10 includes a valve closurebody 12 which is forced by a compression spring 13 against its valveseat formed on the cartridge 7. Moreover, a preferably cup-shapedholding element 14 for guiding, bearing and holding the compressionspring 13 is provided in the valve cartridge 7, with the holding element14 being positively connected to the cartridge 7. Provided in theholding element 14 is at least one port 24 for the passage of hydraulicor brake fluid.

The pressure valve 11 comprises a valve closure body 15 equallyprestressed by a compression spring 16 against the valve seat thereof.It should be noted that in accordance with FIG. 1, the valve closurebodies 12 and 15 are designed as balls and the compression springs 13and 16 are in the form of helical springs, it being, however, possibleto provide valve closure bodies of a shape other than the ball-shapedbodies 12 and 15. Moreover, the compression springs 13 and 16 presentlyformed as helical springs also can be other suitable pre-loading orspring means.

In addition, FIG. 1 conveys that the suction valve 10 is formed on anaxial end of a cylindrical space for the pump piston 5. The pressurevalve 11, in the practice of the invention, is formed substantiallynormal thereto, i.e. the opening and closing directions of the pressurevalve 11, in relation to the cylindrical space, are provided in adirection substantially radial to the opening or closing directions ofthe suction valve 10.

According to FIG. 1, the pressure valve 11 is arranged on the basesection 9 of the cartridge or of the structural unit 7, respectively;also, it can be provided, with advantage, on the sleeve-type section 8.

In the practice of the invention, the valve cartridge 7 is formed as astructural unit adapted to be mounted and checked separately. The valvecartridge and the structural unit 7, respectively, hence, canadvantageously be checked for their serviceability prior to assemblythereof and externally of the pump housing 2 along with the suctionvalve 10 and the pressure valve 11. Moreover, the piston 5 does not workin the pump housing 2 directly but rather in the valve cartridge 7,especially, in the sleeve-type section 8 of the cartridge 7. Thanks tothe formation of the sleeve-type section 8 on the structural unit 7, thebearing surface of the pump piston 5 is insensitive to deformation,surface defects or other irregularities likely to occur by processingoperations on housing 2. Moreover, the bore for the piston motion is nolonger required to be cured or anodized to provide a certain wearresistance of the bearing surface of the pump piston 5. Anotheradvantage provided by the present invention resides in that the pistonpump 1 can be adapted to enhanced requirements placed upon it, whenemployed, for example, in an ASR or ESP system, by choosing a suitablematerial for the valve cartridge 7 in lieu of changing or modifying thehousing 2 which would involve substantial efforts. In particular, thiswill avoid different strengths of anodized coatings ABS, ASR or ESPsystems.

During operation of the piston pump 1 of the invention, in a pressurestroke phase, during which the pump piston 5 moves outwardly relative tothe center axis M, the pressure of the brake or hydraulic fluid isincreased within a pressure chamber 20. To prevent leakage, it ispossible to circumferentially provide at least one packing 21 within agroove formed on the pump piston 5. However, preferably, the packing isarranged within a groove on the outer periphery of the pump cartridge 7(not shown in FIG. 1). The pressurized fluid within the pressure chamber20 will now force the valve closure body 15 of the pressure valve 11against the bias of the compression spring 15 away from its seat,thereby transmitting pressurized fluid to a pressure fluid user (notshown), e.g. to the wheel brakes of an automotive vehicle. In thatphase, the suction valve 10 is forced against its seat formed in thevalve cartridge 7, to remain closed. In a subsequent suction strokephase, during which the pump piston 5, relative to the axis M, movesinwardly, the pressure valve 11 remains closed, i.e. the valve closurebody 15 is forced by the preloading force of the compression spring 16against its valve seat. During that suction stroke phase, due to theenhanced volume and,the decreased pressure of the fluid within thepressure chamber 20 involved therewith, the suction valve 10 is opened.Subsequently, hydraulic fluid, preferably from a low-pressure reservoir(not shown) is admitted to the pressure chamber 20 via passageway 22.

Referring to FIGS. 2 through 4, the design of the pressure valve 11 of afirst form of embodiment of the valve cartridge 7 of the invention, willbe described hereinafter in closer detail. Provided in section 9 of thevalve cartridge or of the structural unit 7, respectively, is apreferably two-step bore 23 extending in a direction substantiallyvertical or radial to a longitudinal axis L of the cartridge 7. In lieuof the step of the bore 23, a conically shaped section is providedserving as a valve seat for the valve closure body 15. A holding clip 25preferably made of a flexible material is plugged onto the valvecartridge 7 by snap-type connection, engaging a preferably two-stepcircumferential groove 26 on the outer periphery of the valve cartridge7. Provided on the holding clip 25 is the compression spring 16 servingto preload the valve closing body 15 against the seat thereof. Theholding clip 25, in this form of embodiment, is a substantially annularelement, extending about the major part of the outer periphery of thevalve cartridge 7. Approximately centrally of the holding clip 25 isformed a bore 27 to provide, in the open condition of the pressure valve11, a fluid connection between the pressure chamber 20 and a pressurefluid user. Provided about the bore 27, on the inner side of the holdingclip 25 facing the valve cartridge 7, is an annular groove 28 foraccommodating or mounting the compression spring 16 to enable thecompression spring 16 to be mounted, with advantage, jointly with theholding clip 25.

FIGS. 5 and 6 schematically show a longitudinal sectional view of avalve cartridge 7 according to second and third forms of embodiment ofthe present invention. The examples of embodiment shown in FIGS. 5 and 6substantially distinguish from the form of embodiment of a valvecartridge 7 of the invention described in connection with FIG. 2, by thedesign of the suction valve 10, i.e. in particular, by the formation ofthe valve closure body 12 and the holding element 14. Whereas the valveclosure body 12 according to FIG. 6 comprises a semispherical sealingface thus corresponding to the valve closure body 12 according to FIG.2, the valve closure body 12 of FIG. 5 comprises an almost planar facewhich can be provided, if so desired, with a step cooperating with thevalve seat formed on the structural unit 7. The holding elements 14 areidentical in FIGS. 5 and 6 and are substantially in the form of a discforced, for example, into the cartridge 7 or connected theretootherwise.

FIGS. 7 and 8 schematically show a valve cartridge 7 according to afourth form of embodiment of the present invention. FIG. 7 conveys thatthe valve cartridge 7 comprises a sleeve-type section 8 wherein, in thepractice of the invention, the pump piston 5 is guided. In lieu of thecoupling ring required in the afore-going examples of embodiment of thepresent invention, in this instance, a compression spring 30 is providedserving for restoring the piston 5. FIG. 8 showing a sectional view ofFIG. 7 taken along the line VII—VII, reveals that a tape 31 of springsteel mounted on the valve cartridge 7 by caulking V is provided forpreloading the valve closure body 15 of the pressure valve 11. If caulkV is eliminated, it is nevertheless possible for the preloading meansfor the valve closure body 15 to be formed integrally with a holdingclip or the like.

FIG. 9 reveals a schematically shown longitudinal sectional view of avalve cartridge 7 according to a fifth form of embodiment of the presentinvention. As opposed to the previously described forms of embodiment,the valve cartridge or the structural unit 7, respectively, in thisembodiment is of a substantially constant outer diameter. To preload thevalve closing body 15 of the pressure valve 11, a leaf spring 32 isprovided which is arranged substantially in parallel to the longitudinalaxis L of the cartridge 7. The leaf spring 32, on one end thereof, isbent to be inserted into a recess 33 formed almost in parallel to thelongitudinal axis L. The tension of the bent end firmly holds the leafspring 32 within the recess 33. The leaf spring 32 always forces thevalve closure body 15 in the vertical direction onto its valve seat. Thevalve cartridge 7 can be made of steel or a plastic material.Preferably, the valve cartridge 7 is made of plastic material because itis thereby possible to mold the valve seats simultaneously duringmanufacture thereof and to integrate the bearing surface for the pumppiston 5. As the cylindrical bore, if the valve cartridge is made ofplastic material, preferably, has a smaller cone to extract the core,the piston 5 is made to have the same cone. These two cones will beadjusted in the working point of the piston pump 1 in relation to thework cycle of the cylindrical bore 34 and the pump piston 5 to achievethe lowest possible play during operation of the piston pump 1. Aclosure lid 35 is caulked in pressure-tight manner into the pump housing12 to thereby eliminate a packing.

Now, referring to FIGS. 10 through 12, a sixth form of embodiment of avalve cartridge 7 of the invention will now be described in closerdetail. A two-step radial bore 39 is formed within valve cartridge 7.Inserted in the outer section of the radial bore 39 exceeding the innersection is a gasket 40 serving as a valve seat for the pressure valve11. The gasket 40, preferably, is made of a rigid plastic material, suchas PEEK. A leaf spring 41 superposed on gasket 40 under prestress, atthe same time serves as a valve closure body and as a preloadingelement. The leaf spring 41 is located, in the axial direction, on theouter side of the valve cartridge 7 and is rigidly connected to theouter side of the valve cartridge 7 by a welded connection, caulk or thelike. FIG. 12, in particular, reveals that the leaf spring 41 is mountedat a welding point S on the valve cartridge. The leaf spring 41 issuperposed, under a low prestress, on the gasket 40 in a substantiallyplanar way. Alternatively, the leaf spring 41 may be slightly bent,thereby generating the preload on the gasket 40. Equally, by way ofalternative, the gasket 40 and, hence, the valve seat also in the radialdirection could be slightly higher than the mounting point of the planarleaf spring 41 to thereby attain a preload of the leaf spring 41. Thesixth form of embodiment of a pressure valve 11 of the invention asshown in FIGS. 10 through 12 involves the advantage of a very compactdesign, consisting of three parts only. The pressure valve 11 isintegrated into the valve cartridge 7 and can be checked innon-assembled condition. It should be noted that the sixth form ofembodiment of the present invention as described in connection withFIGS. 10 through 12, also can be used with a sleeve-type pump.

Referring to FIGS. 13 through 16, a seventh form of embodiment of thevalve cartridge 7 of the invention will be described hereinafter incloser detail. As opposed to the sixth form of embodiment of theinvention as described in FIGS. 10 through 12, no additional gasket 40serving as a valve seat is provided in the seventh form of embodiment.In place, a substantially ring-shaped bead 42 formed about the bore 39serves as the valve seat.

Especially in case the valve cartridge 7 is made of a plastic material,such as PEEK, the ring-shaped bead 42 can be simultaneously moldedduring manufacture of the valve cartridge 7, especially so when producedby injection molding. If the valve cartridge 7 is produced by injectionmolding, the valve seat, i.e. the ring-shaped bead 42, may be slightlyinclined or even slightly bent, thereby conforming to the contour of theleaf spring 41. It should be noted that the seventh form of embodimentof the present invention, in particular, the design of the pressurevalve 11 as shown in FIGS. 13 through 16, can also be employed with asleeve-type pump.

FIGS. 17 and 18 schematically show an eighth form of embodiment of thepresent invention. The pressure valve 11 is integrated within the valvecartridge 7 as it is in the previously described forms of embodiment.The bore 39 is of a two-step configuration. The stepped edge of the bore39 serves as a valve seat for the spherically designed valve closurebody 15 of the pressure valve 11. To preload the valve closure bodyagainst the valve seat thereof, a flexible ring-shaped element, e.g. theEPDM tube 45, is provided keeping down the valve closure body 15 by itsflexibility, forcing it against the valve seat. The valve cartridge isprovided with a circumferential groove 46 into which is placed andpositioned the EPDM tube 45. To enable the brake fluid to be dischargedfrom the bore 39 at a predetermined point thereof, an axial cut 47 isprovided on the outer side of the valve cartridge 7 at the point of thevalve closing body 15, extending along both sides of the passageway 39.Moreover, the cut 47 permits a pressure compensation so that the EPDMtube 45, during a conventional brake process, i.e. when pressure isapplied to force the ball 15 against the seat thereof, is not forcedinto the bore 39. The pressure valve 11 as shown is made of twocomponents only, namely the valve closure body 15 and the EPDM tube 45that can both be produced in a simple and cost-effective way. The valveclosure body 15, preferably, is a standardized part, while the EPDM hose45 can be cut from a commercially available EPDM tube to the requiredsize. In addition to the compact design, this form of embodiment offersthe special advantage that the pressure valve 11 involves fewtolerances. Another advantage of the embodiment as shown resides in thatassembly thereof need not necessarily be in rectified form, therebyfacilitating the assembly. The EPDM hose 45, in the embodiment as shown,forms an additional throttled or restricted point in the flow directionbehind the pressure valve 11, thereby reducing the noise developmentduring closure of the valve 11 as has been found by tests.

Referring to FIGS. 19 and 20, a ninth form of embodiment of the presentinvention will be described hereinafter in closer detail. The said ninthform of embodiment as shown in FIGS. 19 and 20, is generally similar tothe eighth form of embodiment as shown in FIGS. 17 and 18; however, itdistinguishes therefrom in that this design of the pressure valve 11, avalve closure element 44 serving as a valve closure body is rigidlyconnected to the EPDM tube, for example, through a two-componenttechnology or by an adhesive connection. The valve closure element 44and the EPDM tube 45 thereby form a pre-mounted unit and can be drawn inwhole across the valve cartridge 7. To facilitate the positioning,preferably the EPDM-tube 45 is provided with a lug 48 engaging a recess49 formed on the outer side of the valve cartridge 7. The valve closureelement 44 in the ninth form of embodiment of the present invention ismade of a rigid plastic material, such as PEEK, as it does not form astandardized part and as it has a more complex contour compared to thespherically shaped valve closure body 15 according to the eighth form ofembodiment of the present invention. FIGS. 21 and 22 schematically showa tenth form of embodiment of the present invention. As opposed to theninth form of embodiment of the present invention, the pressure valve 11is designed as a plate valve. The flat valve closure element 44 is inthe form of a disc or plate and is made of a plastic material, such asPEEK, and is rigidly connected to the EPDM tube 45.

FIGS. 23 through 26 schematically show an eleventh form of embodiment ofthe present invention. The valve cartridge or the structural unit 7,respectively, according to the eleventh form of embodiment of thepresent invention, preferably, is made of a plastic material, such asPEEK. A prestress or valve element 50 preferably also made of a plasticmaterial, such as PEEK, preferably comprises an integrally formedclosure element 44 serving as a valve closure body, and an arm 51serving for preloading. The closure element 44 is of a substantiallyspherical shape. The arm 51 is of a substantially flat and tongue-shapedconfiguration. Fixed by a weld connection or the like to the end of arm51 opposite the closure element 44, on the valve cartridge 7, is thevalve element 50. To attain a good weld connection between the valveelement 50 and the valve cartridge 7, the two components, preferably,are made of the same material. The arm 51 not only serves to fix thevalve element 50 to the valve cartridge 7 but also to provide a springforce for prestressing the valve closure body 44 against the valve seatthereof formed as a bore 39. The valve element 50 preferably is adie-cast part. Thanks to the design of the valve element 50 as suggestedby the invention, the valve closure body no longer can be pushed out ofthe seat by a pressure pulse as it can according to the prior state ofart. The assembly of the pressure valve 11 is effected in that theclosure body 44 is forced onto the valve seat by a hold-down or stamp54. Another hold-down or stamp 55 forces the end of arm 51 oppositesection 50 onto the valve cartridge 7, welding the two componentstogether. By holding down the arm 51, a bias of the arm 51 is attained,with the arm 51 being connected to the valve cartridge 7 in the samerun. Holding section 50 down on the valve seat during the weldingoperation will insure a sealing fit of the said section 50 on the valveseat. It should be noted that, advantageously, the tolerances of thepressure valve 11 can be offset by a tolerance compensation T in theweld connection.

FIG. 27 schematically shows a longitudinal sectional view of a twelfthform of embodiment of the present invention. The said twelfth form ofembodiment of the present invention as shown in FIG. 27 is generallysimilar to the fifth form of embodiment as shown in FIG. 9; however, itdistinguishes in that the axially extending leaf spring 32, on an unbentend section opposite ball 15, is secured by a weld connection S, e.g. bylaser or caulk V, to a valve cartridge 7 made of metal.

Referring to FIGS. 28 through 31, a thirteenth form of embodiment of thepresent invention will be explained hereinafter in closer detail. Thepressure valve 11 comprises a spherical valve closure body 15 preloadedagainst a radial bore 39 by a holding clip 60. According to across-sectional view of FIG. 17, the holding clip 60 substantially is ofa U-shaped configuration. The holding clip 60 is punched from a steelsheet and comprises two leg sections 61 and 62 in which recesses 63 ad64, respectively, are provided. The valve cartridge 7 is made of aplastic material and is flattened at the sides thereof. The valvecartridge 7, at the flat sides thereof, includes projections 65 and 66that could also be designated by lugs which are injection-molded duringmanufacture of the valve cartridge 7.

The recesses 63 and 64 in the leg sections 61 and 62, respectively, ofthe holding clip 60 engage the projections 65 and 66, respectively,laterally formed on the valve cartridge 7. A flap 68 which can also bedesignated by spring tongue, is formed in a base section 67 of theholding clip 60, which flap holds the valve closure body 15 biasedagainst the valve seat thereof. It should be noted that the recesses 63,64 and the recess 70 required for forming the flap 68 are formed whenpunching the outer contour of the holding clip 60. Subsequently, the legsections 61 and 62 are bent. During formation of the holding clip 60,the valve preloading element, i.e. flap 68 is, therefore, not bent.During bending of the holding clip 60, a corresponding predeterminedbias of the leg sections 61 and 62 vis-à-vis the flattened sides of thevalve cartridge 7 may be provided to prevent the holding clip 60 fromdisengaging the valve cartridge 7, and the flap 68 from disengaging thevalve closure body 15, respectively. FIGS. 30 and 31 convey that the legsections 61 and 62 are formed approximately in the center of the basesection 67 of the holding clip 60 and are approximately half the widthof the base section 67.

FIGS. 32 and 33 schematically show a variant for securing the holdingclip 60 to the valve cartridge 7. FIGS. 32 and 33 convey that accordingto that variant, the ends 71 and 72, respectively, of the leg sections61 and 62 are folded. The valve cartridge 7 substantially of a circularcross-section according to this variant of the invention, on the outerside thereof is provided with two recesses 73 and 74. The radial bore 39and the recesses 73 and 74, respectively, are arranged approximatelyequidistantly across the outer circumference of the valve cartridge 7.When mounting the holding clip 60 on the valve cartridge 7, the foldedends 71 and 72 engage the conforming recesses 73 and 74, respectively.An advantage involved with this variant resides in that the bendingrequired for snapping to force the flap 68, permanently in preloadedcondition, onto the valve cartridge 7 mainly takes place within thenarrow leg sections 61 and 62 of the holding clip 60. Removing thespring tongue 68 from the valve closing body 15 can thus be prevented bythe shaping of the leg sections 61 and 62.

It should be noted that the selected way of securing the holding clip 60to the valve cartridge 7 according to FIGS. 28 through 33 will preventthe tongue 68 from twisting.

FIGS. 34 and 35 schematically show a fourteenth form of embodiment ofthe present invention. The valve cartridge 7 substantially is of abipartite configuration, comprising a sleeve 77 and a closure lid 78.The pressure valve 11, within the sleeve 77, is substantially radiallydesigned. The suction valve 10, within the closure lid 78, issubstantially axially designed. The pressure valve 11 and the suctionvalve 10, in general, are of a similar design as the afore-describedembodiments of the invention. The valve cartridge 7 is secured, e.g. bycaulking, in an accommodating bore 79 within the pump housing 2.Subsequently, the bore 79 is sealed in a pressure-tight way by a closurelid 80, especially by caulking. Preferably, the closure lid 78 is sealedby an O-ring 81 against the sleeve 77 However, the O-ring 81 is notabsolutely required as leakage will occur only in the pressure build-upphase. In the event that no packing is provided between the sleeve 77and the closure lid 78, the fit between these two components should berelatively tight. It should be noted that the bipartite formation of thevalve cartridge 7, at a first glance, appears to be disadvantageousbecause costs are increased in view of the larger number of parts.However, in a one-piece design of the valve cartridge 7 as shown, forexample, in the thirteenth embodiment of the present invention, securingof the suction valve 19 constitutes a manufacturing and cost problem inview of the small diameter of the cylinder. On the whole, the bipartitedesign of the valve cartridge could, therefore, be more cost-effectiveand easier to manufacture.

Referring to FIGS. 36 through 41, a fifteenth form of embodiment of thepresent invention will be described hereinafter. The pressure valve 11radially formed within the valve cartridge 7 comprises a valve closurebody 15 of a plastic material, such as PEEK. This is of advantagebecause a valve closure body of steel would gradually penetrate thevalve seat resulting in a porosity of the pressure valve 11. The valveclosure body 15 comprises an upper section 85 including a slightcurvature 86 formed on the upper side thereof Moreover, the valveclosure body 15 is provided with a guiding section 87 in the form of ajournal which is guided within the radial bore 39. The guiding section87 is formed so as to enable brake fluid to flow past the same. Inaddition, the guiding section 87 includes three ribs 88 formed to bestaggered by about 120° as best shown by FIGS. 40 and 41. The curvature48 serves to permanently force the guiding section against the innerface of the bore 39. The valve closure body 15 comprises a sealingsection 89 provided between the section 85 and the guiding section 87 toinsure that the valve seat is sealed across the surface thereof. Forthis purpose, the sealing section 88 is of a substantially sphericalconfiguration. The guiding section 87, during opening and closing of thepressure valve 11, causes friction on the inner face of the radial bore39, thereby attenuating the valve closure body 15. This is of advantagebecause especially with low numbers of revolution of a motor actuatingthe piston pump, a whistling noise is likely to occur probably to beattributed to vibrations of the valve closure body 15. The frictionimposed on the movement of the guiding section 87, hence, will reducethat kind of noise. By way of alternative, in the practice of theinvention, such an attenuation can be generated when using a helicalcompression spring in lieu of the leaf spring 32 forming the preloadingelement for the pressure valve 11, or by using a conical spring equallyeffecting an attenuation by causing friction on the coils thereof.

FIGS. 42 and 43 schematically show a sixteenth form of embodiment of thepresent invention. The valve cartridge 7 comprises a highpressure-resistant pressure valve 11. A single element 90 is provided asit is in the eleventh form of embodiment of the present inventionaccording to FIG. 23, wherein are integrated a valve closure body,spring means for preloading the valve closure body and mounting meansfor securing the spring means to the valve cartridge 7. The element 90is produced by injection molding from a high temperature-resistantthermoplastic material, such as PEEK. The element 90 comprises a guidingsection 91, a valve closing section 92 and a holding clip section 93.The guiding section 91 substantially is a journal having four cross-wisearranged webs 93 and serving to guide the spherically designed valveclosure section 92. The formation of the guiding section 91 as shownserves especially for noise reduction, as previously set out. Asconveyed by FIG. 43, the holding clip section 93 is of a U-shapedcross-section. The holding clip section 93 comprises a basis 94 and twolegs 95, 96 bent in a direction perpendicular thereto. Formed on theinner side of the ends of the legs 95, 96 are two locking lugs 97 and98, respectively, for securing the element 90 to the valve cartridge 7.The valve cartridge 7 comprises, on the sides thereof, undercuts 99, 100engaged by the locking lugs 97 and 98, respectively, thereby enablingthe element 90 to be secured thereto by simply plugging the same ontothe valve cartridge 7. It should be noted that in this form ofembodiment the holding clip section 93 is biased in two directions so asto result in a predetermined minimum contact force on the closure bodysection 92 and a playfree fit of the locking lugs 97 and 98 within theundercuts 99 and 100, respectively.

FIGS. 44 and 45 schematically show seventeenth and eighteenth forms ofembodiment of the present invention. The valve cartridge 7 comprises aneasy-to-mount suction valve 10, insuring favorable flow conditions. Thesuction valve 10 comprises a valve closure body 12 made of a hightemperature-resistant thermoplastic material, such as PEEK. The valveclosure body 12 comprises a sealing section 110 and a guiding section111. The sealing section 110 is conically designed in accordance withthe valve seat thereof. The guiding section 111 serving for guiding thevalve body 12 in an axial bore 113 within the valve cartridge 7,includes four axial ribs 114 on the outer sides of which projections 115are formed for bearing, on the suction side, one end of a compressionspring 116 designed as a helical spring. The other end of thecompression spring 116 is also disposed on the suction side at a stepformed within the bore 113. The forms of embodiment as shown areparticularly advantageous because an otherwise required holding elementfor the compression spring 116 can be eliminated. Moreover, thearrangement of the compression spring 116 within a step of the axialbore 113 involves the advantage that the brake fluid taken in is notrequired to be sucked through the coils of the compression spring 116,thereby substantially reducing the flow resistance in a suction strokeof the pump piston 5.

In the nineteenth form of embodiment of the present inventionschematically shown in FIG. 46, the valve seat for the suction valve 10, i.e. in particular, the axial bore 113, is not formed within the valvecartridge 7 but rather in a separate valve seat element 120. The valveseat element 120 is mounted within the axial bore of the valve cartridge7, thereby enabling a preliminary assembly of the suction valve 10externally of the valve cartridge 7.

Referring to FIGS. 47 and 48, the twentieth form of embodiment of thepresent invention will be described hereinafter. The pressure valve 11comprises a spherical valve closure body 15 which is forced by a springsection 130 of a holding clip 131 of steel sheet secured to the valvecartridge 7, against the valve seat thereof formed within the radialbore 39. The holding clip 131 comprises, in addition to the springsection 130, an annular section 132 formed vertical thereto which isalmost closed, which section 132, for mounting purposes, is drawn, fromthe front side, in the axial direction, across the valve cartridge 7 andis held, in positive connection, almost throughout the entire outercircumference of the valve cartridge 7. By axially drawing the annularsection 132 across the valve cartridge 7 only the annular section 132 isexpanded, for which reason the spring section 130 also after having beenmounted still exhibits a high clamping force. The spring section 130 isbent in a substantially U-shaped way on the side facing away from thevalve closure body 15 to attain a maximum resilient length with aminimum assembling length. Furthermore, bending the spring section 130by 180° always enables the valve closure body 15 to be normally forcedagainst the valve seat thereof. Forcing the valve closure body 15 in theoblique direction is disadvantageous because an oblique introduction offorce through the spring element will result in a one-sided wear of thevalve seat. In this respect, it should be noted that in some of thepreviously described embodiments of the invention (see, in particular,FIGS. 23, 28 and 34), the radial bore is of an oblique design to forcethe valve closure body 15 always in the vertical direction against thevalve seat thereof.

To preclude axial twisting and displacement of the holding clip 131 onthe valve cartridge 7, the holding clip 131 according to thetwenty-first form of embodiment of the present invention shown in FIG.49, comprises a section 140 bent in a U-shaped way in the radialdirection and engaging a bore 141 formed on the outer side of the valvecartridge 7. The bore 141 is provided between the radial bore 39 and theend of the spring section 130 bent in a U-shaped way. It is, of course,possible to provide other suitable means for centering the holding clip131, such as a projection formed on the holding clip 131.

The formation of the holding clip 131 of the pressure valve 11 accordingto the twentieth and twenty-first forms of embodiment of the presentinvention is, therefore, particularly advantageous because in case of acured valve cartridge 7 mounting of a spring element, such as leafspring 32 as shown in FIG. 16, by caulking, will not be possible. Theneed to use a cured valve cartridge 7 will, therefore, arise from thefact that the pump piston 5 at high pump pressures, e.g. in permanentoperation at about 200 bar, will “dig” into the valve cartridge 7.

FIGS. 50 through 52 show a twenty-second form of embodiment of thepresent invention. The valve cartridge 7, in the practice of theinvention, comprises a suction valve 10 and a pressure valve 11 formingindividually handled structural units. The valve cartridge or thestructural unit 7, respectively, can be inserted by means of an O-ring145, in a pressure-tight manner, in a pump housing (not shown). Thearrangement of the O-ring 145 at this place is to be preferred to thearrangement thereof on the piston as already described in theafore-going. The pressure valve 11 comprises a leaf spring 131 which,compared to the previous forms of embodiment, is differently connectedto the valve- or pump cartridge 7. The forms of embodiment according toFIGS. 9, 34 and 35 encounter the problem that especially the obliquelycut groove for accommodating the leaf spring of pressure valve 11involves a cost-intensive formation of the groove on that valvecartridge 7. If the leaf spring as shown in FIGS. 10 through 16, 23through 27 and 36 and 37 is caulked or welded to the pump cartridge 7,the leaf spring will be connected to the valve cartridge 7 in an area ofmaximum strain. For that reason it is suggested in this form ofembodiment to shift the attachment of the leaf spring 131 to the valvecartridge 7 away from the high-strain bending zone 146 of the spring131. Advantageously, the leaf spring 131 here comprises two sections147, 148 engaging a groove 149 of the cartridge 7. The leaf spring 131,advantageously, is connected by means of a plurality of caulking areas150 on steps 151 of groove 149 to cartridge 7. Caulking V,advantageously, is effected at an adequate lateral space from thehigh-strain bending zone 146. The groove 149 can be manufactured at lowcost, for example by turning a metal cartridge or by casting a plasticcartridge.

The twenty-third form of embodiment of the present invention asillustrated in FIGS. 53 through 55 substantially corresponds to theprevious embodiment so that reference is made to the contents thereof.However, the leaf spring 131 comprises a folded spring section 130,thereby enlarging the resilient length of the spring 131 and enablingthe entire leaf spring 131 to be held shorter.

The twenty-fourth form of embodiment of the present invention accordingto FIGS. 56 through 58 shows a valve cartridge 7 with a pump piston 5and a leaf spring 131. In this form of embodiment the leaf spring 131 isfolded in a way corresponding to the preceding embodiment, thuscomprising a resilient section 130. The difference resides in thatsections 147, 148 of spring 131 are provided with leg-type extensions152, 153, thereby enabling the spring 131 to be clamped onto the valvecartridge 7 especially for pre-mounting purposes. Especially in caseswhere the structural unit or the valve cartridge 7, respectively, ismade of metal, this form of embodiment suggests to shift the caulk V atboth sides to the level of the bore axis or longitudinal axis L of thevalve cartridge 7, thereby substantially reducing the mechanical load ofa housing unit (not shown) holding the cartridge 7 during the caulkingprocess. The caulked material of cartridge 7 shown in the form of acircular arc in FIG. 57 flows into grooves 154 of the leaf spring 131,thereby insuring a positive connection between spring 131 and valvecartridge 7.

What is claimed is:
 1. A piston pump of the type used in pressure fluidconveyance in hydraulic, slip-controlled brake systems, comprising: apump housing having a bore therein, at least one piston residing in saidbore, a suction valve and a pressure valve, wherein the suction valveand the pressure valve are formed on a structural unit wherein thevalves are arranged with respect to one another in a substantiallyvertical relationship, and wherein said structural unit communicateswith said bore, wherein the suction valve is arranged axially andwherein the pressure valve is arranged radially relative to alongitudinal axis of the structural unit, wherein the pressure valvefurther includes a valve closure body and a valve seat, wherein thevalve closure body is biased by a preloading element against the valveseat thereof, wherein the preloading element is formed on a clip,wherein the clip includes first and second sections formed substantiallyvertical relative to one another, wherein the first section is attachedto the structural unit and the second section is provided to preload thevalve closure body.
 2. A piston pump according to claim 1, wherein thepreloading element and the valve closure body are integrally formed. 3.A piston pump according to claim 1, wherein the preloading element isdesigned connected to the structural unit.
 4. A piston pump according toclaim 1, wherein the second section comprises a tongue portionsubstantially bent by 180°.
 5. A piston pump according to claim 1,wherein the preloading element is designed as a leaf spring.
 6. A pistonpump according to claim 36, wherein the leaf spring extends parallel tothe longitudinal direction of the structural unit.
 7. A piston pumpaccording to claim 5, wherein the leaf spring is connected to thestructural unit.
 8. A piston pump according to claim 1, wherein thevalve seat is formed on a valve bore, wherein the valve closure bodyincludes a guiding section for guiding the valve closure body within thevalve bore.
 9. A piston pump according to claim 8, wherein the valveclosure body includes a sealing section.
 10. A piston pump according toclaim 9, further including means for bearing a first end of the springelement, wherein said bearing means are formed on an outer side of theguiding section.
 11. A piston pump according to claim 10, furtherincluding bearing means for bearing a second end of the spring element.12. A piston pump according to claim 9, wherein the structural unitincludes a base section and a section of sleeve-type design.
 13. Apiston pump according to claim 12, wherein the pressure valve is formedon the section of sleeve-type design.
 14. A piston pump according toclaim 13, wherein the structural unit comprises a sleeve-type section inwhich the piston is guided.
 15. A piston pump according to claim 12,wherein the suction valve is formed on the base section.
 16. A pistonpump according to claim 12, wherein the base section is formed as aseparate structural unit.
 17. A piston pump according to claim 1,wherein the structural unit is of a substantially constant outerdiameter.
 18. A piston pump according to claim 1, wherein the structuralunit is secured within a housing of the piston pump by caulking orclinching.
 19. A piston pump according to claim 1, wherein thestructural unit is made of a plastic material.
 20. A piston pumpaccording to claim 1, wherein the piston is formed into a conicalconfiguration.